Healer

A Healer is more of a role than a class. Due to this fact, this class page is handled a bit differently.

Choose another Spellcasting Class- Pact Mage (most obvious choice), Druid (also good), Guild Sister (their flexibility is somewhat wasted on this), Bard (constantly being able to heal for a single PP is nice, I guess), or Guild Mage (works fine)
The Patron of Death feat grants a healing Supernatural Ability that can be used, but all other relevant feats are other Spellcasting class feats.
Spells- Here's the list of healing and recovery spells to choose to be a healer

Regeneration
Damage Resistance
Cleanse Creature
Channel energy
Restoration
Restore Life

For the classic RPG Healer consider combining with Melee Tank Fighter or Melee CC Fighter classes